Heliox is a mixture of helium and
oxygen, with not less than 20 % oxygen. Usual combination ratio
is 70 parts helium to 30 parts oxygen or 79 parts helium to 21
been used for more than 70 years in medical applications and is
widely used in diving applications. Heliox as a breathable gas
for medical treatment in pulmonary disease was first introduced
in 1934 by Barach.
Helium is one of the lightest
gas, and it replaces nitrogen present in air which is much
heavier. Helium is an inert gas i.e. it does not react with
other substances. As Heliox is three times lighter than air, is
easier to breath and faces much less resistance in airways.
Heliox is administered in a
similar fashion as any other breathing gas. Heliox can be given
by high flow nasal cannula, hood or facemask. Room air should
not enter heliox breathing system as that will dilute the gas
and increase its density.
Heliox can be used for jet
nebulization. As heliox is a lighter gas, high flow rates are
needed to produce medically useful aerosol.
Uses of Heliox:
Beneficial effects have been
observed in patients with:Croup
Acute airway obstruction
Foreign body aspiration
Risks with Heliox system:
Infants who are administered
Heliox via hood face risk of hypothermia. Heliox has high
thermal conductivity and there is consequent risk of hypothermia
when the gas temperature is 36°C, especially when heliox is
administered for long periods. The risk of hypothermia can be
avoided with adequate warming and humidification of the heliox,
using standard devices.
Faulty gas mixture containing
less than 20 % oxygen is the cause for hypoxia. This risk is
reduced by never administering 100% helium to a closed system,
and always using heliox that contains at least 20% oxygen.
Oxygen monitor in a breathing system should always be used.
Delivery of Too Much Volume.
If the mechanical ventilator
delivers more than the set volume, there is a risk of
volume-induced injury, pressure induced injury, or hypocarbia.
This is of particular concern with ventilators not designed for
Running a jet nebulizer with
too low a flow of heliox can result in inadequate aerosol
delivery to the patient at a time when aerosol delivery is